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Air Quality and Health Effects Associated with the Operation of BAe 146-200 Aircraft
Abstract
Poor air quality and health complaints from flight crews operating BAe-146 aircraft, requiring admission to emergency departments on several occasions, led to an investigation into the source of these problems. Health complaints could be classified as those consistent with exposure to carbon monoxide, respiratory irritants, and possible neurological agents. Cabin air is bled off from the engine's combustion air, passes through a catalytic converter to clean the air from oil contaminants, is cooled from 550° to 50°C, and enters the cabin after it passes through an airpack unit which conditions the air as appropriate. Excessive oil leakage from oil seals overloaded the catalytic converter, allowing smoke and lubricating oil components to enter the cabin. A complaint aircraft air, during a test flight, was found to contain oil contaminants including siloxane lubricating oils, as well as methylated propane and butane ester derivatives. Tricresyl phosphates, known to be neurotoxic, were identified in bulk oil samples, but could not be demonstrated in the cabin air. Air quality measurements in a problem aircraft tested on the tarmac indicated carbon monoxide at 3 ppm and carbon dioxide at 900 ppm. Air quality measurements during normal commercial flights of three noncomplaint aircraft (two BAe-146s and one de Haviland Dash 8-100) showed no detectable levels of carbon monoxide, 800 to 2700 ppm for carbon dioxide, and 19.6 to 21.9 percent for oxygen. Carbon dioxide and oxygen levels would change predictably during takeoff and landing for the former and pressurization and depressurization for the latter. Carboxyhemoglobin levels in four individuals admitted to emergency departments ranged from 0.7 to 2.0 percent. Since no direct carbon monoxide measurements were available during these incidents, it was recommended that potential problem aircraft be equipped with datalogging carbon monoxide monitors to identify or eliminate carbon monoxide exposure as a problem.
... PBDEs (air sampling) <0.4-1.3 ng/m 3 * 2100 ng/m 3 Allen et al., 2013b PBDEs (dust sampling) 20-495,000 ng/g* 2,600,000 ng/g Allen et al., 2013a TVOCs 7 μg/m 3 -4 ppm* >10 ppm Crump et al., 2011;Guan et al., 2015;Rosenberger, 2018;Rosenberger et al., 2016;Solbu et al., 2011;Wang et al., 2014 Carbon Monoxide <LOD -3 ppm >5 ppm Crump et al., 2011;Lee et al., 2000;Nagda et al., 1992;Rosenberger, 2018;Van Netten, 1998 Carbon Dioxide 520-2700 ppm 5177 ppm Giaconia et al., 2013;Guan et al., 2019;Guan et al., 2015;Lindgren and Norback, 2002;Lee et al., 2000;Li et al., 2014;Lindgren et al., 2007;Nagda et al., 1992;Rosenberger, 2018;Van Netten, 1998;Wieslander et al., 2000 Ozone <LOD -117 μg/m 3 ** 302 μg/m 3 ** Lindgren and Norback, 2002;Lee et al., 2000;Nagda et al., 1992;Rosenberger, 2018;Rosenberger et al., 2016;Spengler et al., 2004 TCPs (air sampling) <LOD -2.9 μg/m 3 51.3 μg/m 3 Crump et al., 2011;Denola et al., 2011;de Ree et al., 2014;Rosenberger, 2018;Rosenberger et al., 2016, Solbu et al., 2011van Netten, 2009;Van Netten, 1998 (Farrauto and Armor, 2016). Deicing before takeoff can contribute to elevated contamination within the cabin (Rosenberger, 2018). ...
... PBDEs (air sampling) <0.4-1.3 ng/m 3 * 2100 ng/m 3 Allen et al., 2013b PBDEs (dust sampling) 20-495,000 ng/g* 2,600,000 ng/g Allen et al., 2013a TVOCs 7 μg/m 3 -4 ppm* >10 ppm Crump et al., 2011;Guan et al., 2015;Rosenberger, 2018;Rosenberger et al., 2016;Solbu et al., 2011;Wang et al., 2014 Carbon Monoxide <LOD -3 ppm >5 ppm Crump et al., 2011;Lee et al., 2000;Nagda et al., 1992;Rosenberger, 2018;Van Netten, 1998 Carbon Dioxide 520-2700 ppm 5177 ppm Giaconia et al., 2013;Guan et al., 2019;Guan et al., 2015;Lindgren and Norback, 2002;Lee et al., 2000;Li et al., 2014;Lindgren et al., 2007;Nagda et al., 1992;Rosenberger, 2018;Van Netten, 1998;Wieslander et al., 2000 Ozone <LOD -117 μg/m 3 ** 302 μg/m 3 ** Lindgren and Norback, 2002;Lee et al., 2000;Nagda et al., 1992;Rosenberger, 2018;Rosenberger et al., 2016;Spengler et al., 2004 TCPs (air sampling) <LOD -2.9 μg/m 3 51.3 μg/m 3 Crump et al., 2011;Denola et al., 2011;de Ree et al., 2014;Rosenberger, 2018;Rosenberger et al., 2016, Solbu et al., 2011van Netten, 2009;Van Netten, 1998 (Farrauto and Armor, 2016). Deicing before takeoff can contribute to elevated contamination within the cabin (Rosenberger, 2018). ...
... PBDEs (air sampling) <0.4-1.3 ng/m 3 * 2100 ng/m 3 Allen et al., 2013b PBDEs (dust sampling) 20-495,000 ng/g* 2,600,000 ng/g Allen et al., 2013a TVOCs 7 μg/m 3 -4 ppm* >10 ppm Crump et al., 2011;Guan et al., 2015;Rosenberger, 2018;Rosenberger et al., 2016;Solbu et al., 2011;Wang et al., 2014 Carbon Monoxide <LOD -3 ppm >5 ppm Crump et al., 2011;Lee et al., 2000;Nagda et al., 1992;Rosenberger, 2018;Van Netten, 1998 Carbon Dioxide 520-2700 ppm 5177 ppm Giaconia et al., 2013;Guan et al., 2019;Guan et al., 2015;Lindgren and Norback, 2002;Lee et al., 2000;Li et al., 2014;Lindgren et al., 2007;Nagda et al., 1992;Rosenberger, 2018;Van Netten, 1998;Wieslander et al., 2000 Ozone <LOD -117 μg/m 3 ** 302 μg/m 3 ** Lindgren and Norback, 2002;Lee et al., 2000;Nagda et al., 1992;Rosenberger, 2018;Rosenberger et al., 2016;Spengler et al., 2004 TCPs (air sampling) <LOD -2.9 μg/m 3 51.3 μg/m 3 Crump et al., 2011;Denola et al., 2011;de Ree et al., 2014;Rosenberger, 2018;Rosenberger et al., 2016, Solbu et al., 2011van Netten, 2009;Van Netten, 1998 (Farrauto and Armor, 2016). Deicing before takeoff can contribute to elevated contamination within the cabin (Rosenberger, 2018). ...
Occupational exposure to oil fumes, organophosphates, halogenated flame retardants, and other volatile and semi-volatile contaminants is a concern within the aviation industry. There is no current consensus on the risk attributed to exposure to these chemical classes within the aircraft cabin. Contaminant concentrations rarely exceed conventional air quality guidelines, but concerns have been raised about these guidelines' applicability within the aircraft environment. This systematic review, the largest and most comprehensive completed to date on the subject matter, aims to synthesize the existing research related to chemical and other exposures inside the aircraft cabin to determine the occupational risk that may be attributed said exposure, as well as, determine knowledge gaps in source, pathway, and receptor that may exist. The Science Direct, Scopus, and Web of Science databases were queried with five search terms generating 138 manuscripts that met acceptance criteria and screening.. Several potential areas requiring future examination were identified: Potable water on aircraft should be examined as a potential source of pollutant exposure, as should air conditioning expansion turbines. Historical exposure should also be more fully explored, and non-targeted analysis could provide valuable information to comprehend the aircraft cabin exposome. Occupational risk under typical flight scenarios appears to be limited for most healthy individuals. Contaminants of concern were demonstrated to be extant within the cabin, however the concentrations under normal circumstances do not appear to be individually responsible for the symptomologies that are present in impacted individuals. Questions remain regarding those that are more vulnerable or susceptible to exposure. Additionally, establishing the effects of chronic low dose exposure and exposure to contaminant mixtures has not been satisfied. The risk of acute exposure in mitigable fume events is substantial, and technological solutions or the replacement of compounds of concern for safer alternatives should be a priority.
... Symptoms of Aerotoxic syndrome are diverse and include headaches, confusion, loss of balance, muscle weakness, numbness and neurobehavioral problems (Abou-Donia, 2003;Michaelis, 2003;Coxon, 2002;van Netten, 1999;Montgomery et al., 1977). As a consequence of the proposed association of exposure to ToCP with Aerotoxic syndrome symptoms, the level of ToCP in commercial TCP mixtures has been reduced over time (DeNola et al., 2008). ...
... In literature, health problems that are mentioned in a possible relation with bleed air exposure or the alleged Aerotoxic syndrome include nausea, headaches, confusion, loss of balance, lightheadedness, muscle weakness, shortness of breath, movement disorders, numbness, and paraesthesias. Neurobehavioral problems include cognitive dysfunction, emotional instability, depression, sleep and anxiety disorders (Abou-Donia, 2003;Michaelis, 2003;Coxon, 2002;van Netten, 1999;Montgomery et al., 1977). The symptoms associated with bleed air exposure or the Aerotoxic syndrome are thus diverse, the relation of these symptoms with OPIDN is unclear, and there is no common pattern of symptoms that can readily be identified as being characteristic of ''cabin air quality incidents'' (CAA, 2004). ...
... 14 Other studies of exposures in airplanes exist in the literature, including a 1983 study of eighty nine cases of smoke/fumes in the cockpit in the US Air Force, 15 a study of 1983 study of Boeing 747 flight attendants in the USA, 16 and a 1998 study of BAe 146 flight crews in Canada over a four-month period. 17 There are common themes in symptom clusters in these studies, as shown in the table below. The range of symptoms in these studies is quite broad, affecting many body systems. ...
... In terms of toxicity, a large number of crew are developing symptoms 16,17,22,23 following both short-term and long term repeated exposures. Neurotoxicity is a major flight safety concern, 24 especially where exposures can be intense. ...
Summary Materials used in the operation of aircraft may contain hazardous ingredients, some with significant toxicities, and need care in handling and use. Some maintenance or operational activities, such as leaks or poorly controlled maintenance procedures, can, through contamination of aircraft cabin air, produce unwanted exposures to crew and passengers. Occasionally, such exposures (either short term intense or long term low level) may be of a magnitude to induce symptoms of toxicity. These symptoms are associated with air crew exposure at altitude to atmospheric contaminants from engine oil or other aircraft fluids, temporally juxtaposed by the development of a consistent symptomology of short-term skin, gastro-intestinal, respiratory and nervous system effects, and long-term central nervous and immunological effects. Symptoms from seven case studies, from flight crew and flight attendants in four airlines operating in four countries and in three airplane models are listed. These symptoms may be reversible following brief exposures, but features are emerging of longer term problems following significant exposures. This has significant implications for safety in the aviation industry and occupational health.
... Cabin crew may also be exposed to turbine oils due to the fact that cabin air is bled off from the engine core, and OPs have been suggested as major contaminants of concern in airplane cabin air during so called smoke-in-cabin incidents. [69][70][71][72][73][74] Air monitoring studies for aircraft cabin contamination has also been reviewed, 75 and describes several reports on contamination of cabin air. ...
During the last decade, there has been an increased concern of impact to human health
from exposure to lubricants and organophosphates (OPs) for workers in the aviation
industry. In spite of this concern, neither methods for assessing such exposure nor relevant exposure data for air concentrations of OPs could be found in the scientific literature. This revealed a need for development of such methods and work task related exposure measurements of OPs in the aviation industry in general. The four papers presented in this thesis describe development of sampling methodology and their use in the aviation industry for assessment of OPs in occupational air.
... The mixture is then filtered using high-energy particulate air (HEPA) filtration before entering the cabin. However, small amounts of contaminants may be present in bleed air as a result of leaking engine oil seals, allowing smoke and lubricating oil components to enter the cabin (Gladyszewska-Fiedoruk, 2012;van Netten, 1998). HEPA filters must be at least 99.97% efficient at capturing particles measuring 0.3 lm in diameter, which means that smaller particles such as BC may not be captured by HEPA filters. ...
The volume of passengers carried by airlines increased by 57% globally in the period 2005–2014. This value is more outstanding when observed regionally, especially in developing countries (for example, Brazil experienced a rise of 121% over the same period). This large growth of civil aviation enhances air pollution levels and poses health risks to passengers, airport workers and the population living close to airfields. We measured black carbon (BC) particle concentrations using hand-held devices within different microenvironments of 12 airports and on 41 non-smoking commercial flights, totalling 154 h of data. The largest BC concentrations were found during boarding and disembarking (mean 3.78 μg m⁻³), followed by large concentrations at the airport concourse (mean 3.16 μg m⁻³) and inside parked aircraft with open doors (mean 2.78 μg m⁻³). BC levels were remarkably low when the aircraft were on the ground with the doors closed (mean 0.81 μg m⁻³), with incidental relatively high concentrations (BC at 95th percentile = 2.82 μg m⁻³) suggesting that exhaust plumes from the apron enter the cabin through the ventilation system. The lowest BC concentrations were found during the flights (mean 0.20 μg m⁻³, 95th percentile = 0.52 μg m⁻³). The data show that the concourse and the transit to/from the aircraft contributed disproportionally to the personal exposure and accounted for an average of 52% and 19% of the total exposure during a journey, respectively. The results suggest that these two microenvironments should be targeted to reduce exposure of passengers and airport workers to BC particles.
... S inus disease represents 1 of the most common healthcare problems affecting Americans, with a prevalence of approximately 16% of the population. 1 Airplane cabin air has been shown to have multiple possible respiratory irritants. 2 In addition, changes in barometric pressure in flight may contribute to respiratory conditions. Therefore, there may be an association between commercial airline flight and sinus disease. ...
Background:
Airplane cabin supply air has been shown to contain multiple possible respiratory irritants. In addition, changes in barometric pressure in flight may contribute to specific respiratory conditions. Therefore, there may be an association between commercial airline flight and sinus disease.
Methods:
Participants of the Secondhand-Smoke, Air Quality and Respiratory Health Among Flight Attendants Study were administered an online questionnaire pertaining to their flight experience and respiratory health. Working years, working days per month, and number of trips per month were quantified, as well as smoking exposure and self-reported physician diagnoses of sinusitis, asthma, and rhinitis. The sinonasal outcomes were quantified using a Respiratory Questionnaire Survey (RQS) score. Multivariable analyses were performed to evaluate the associations between flight time and sinus disease.
Results:
A total of 579 participants met the inclusion criteria for this study, with cohort prevalence of sinusitis, asthma, and rhinitis of 25.3%, 14.4%, and 20.5%, respectively. Tertiles 2 and 3 of working days per month were associated with higher RQS scores compared to tertile 1 (p for trend <0.01). Individual symptoms significantly associated with increasing number of working days per month included "need to blow nose," "sneezing," and "thick nasal discharge," and the number of international trips per month was significantly associated with "coughing" and "facial pain and pressure," among other symptoms.
Conclusion:
This is the largest study to analyze the relations between airline flight time and sinonasal disease. The results suggest a possible association between sinusitis diagnosis, symptom scores, and specific sinonasal symptoms, and airline flight time.
... A number of toxicity studies report a consistent range of symptoms in exposed individuals (Rayman, 1983;Van Netten, 1998). Because flight safety can be compromised, due to significant symptoms such as disorientation, blurred vision, impaired memory, altered coordination and so on, attempts have been made to address these problems worldwide. ...
The use of jet-fuel, de-icing fluids, lubricants, hydraulics, engine oil and other fluids, are associated with single repeated/accidental or chronic exposure (s) to ground staff, flight-deck and cabin crew and passengers. These fluids can become airborne in vapor or aerosol phases, and are known to contain neurotoxicants, carcinogens, irritants and other toxic ingredients. Exposures (single or repeated) to these toxic materials are not rare events and some typical failures/working conditions include mechanical failures, seal leaks, and operational procedures, such as take off while fumes detected, pack burn outs. A method for calculation of exposure dose is proposed. The additional impact of exposure to toxicants in conditions of lowered pressure (and reduced oxygen level), other potentiation factors are still largely unknown, but are not presumed to be beneficial. These occupational and public exposures can impact on a range of issues, including: air safety; public liability; ground and air crew safety; control requirements on the supply/ handling/use/disposal of these products; and national and international regulations. A number of toxicity studies report a consistent range of symptoms in exposed individuals (Rayman, 1983; Van Netten, 1998). Because flight safety can be compromised, due to significant symptoms such as disorientation, blurred vision, impaired memory, altered coordination and so on, attempts have been made to address these problems worldwide. These include changes in engine design, drainage, containment, retrofitting of engine filters, modified maintenance and operation and procedures and the like. Some of these changes were developed in past decades or are being currently worked-out while new technologies are being developed that enable significant reduction in concentrations of toxic airborne chemicals. However, while the problem persists, exposure of staff and the public to levels of toxicants that may affect safety and health continues. © 1999 by SAE International and the American Institute of Aeronautics and Astronautics, Inc.
... health symptoms reported by Australian BAe 146 pilots. 1,[5][6][7] Both the BAe 146 pilots and the B757 pilots reported a similar pattern of extensive symptoms at high to moderate rates (including eye, nose and throat irritation, headaches and dizziness, fatigue, feelings of being unwell, concentration difficulties, memory impairment and nausea), although the symptoms were at a higher frequency and with more long-term effects among the BAe 146 pilots. In addition, symptoms occurred not only after specified leak events but also during "nonevent" flights, and were more prevalent on the B757 and BAe 146 than other aircraft. ...
A survey of health symptoms was undertaken in pilots who were members of the British Airline Pilots Association flying the Boeing 737, Boeing 757 and Airbus A320. Six hundred questionnaires were sent out to members, and 106 pilots responded. Survey respondents were predominantly male (104/106) and many had extensive flying experience. With regard to leak events (that is, leaks of engine oil and hydraulic fluids into the aircraft), 93/106 reported that they had been involved in at least one. The total number of incidents reported was estimated to be 1,674+, with all but seven occurring on the B757. Following exposure to the contaminated air, high rates of symptoms were reported by the pilots, including: irritation of the eyes, nose and throat; headaches, light-headedness and dizziness; fatigue, weakness and a decrease in performance; a general increase in feeling unwell; concentration difficulties and confusion; diarrhoea; nausea, vomiting and gastrointestinal problems; numbness (head, limbs, lips, fingers); short-term memory impairment; and joint pain/muscle weakness. These symptoms are a direct breach of US Federal Aviation Regulation 25.831, which includes a specific requirement that cabin air should not cause symptoms of discomfort, fatigue, irritation or toxicity.
... Er is internationaal discussie over mogelijke blootstelling van piloten aan schadelijke stoffen die in de cabinelucht terecht kunnen komen. Al sinds 1977 zijn er publicaties verschenen over vliegtuigbemanningen met symptomen zoals duizeligheid, misselijkheid, tremoren, wazig zien, spierzwakte, desoriëntatie, verlies van kortetermijngeheugen en cognitieve problemen (Montgomery et al., 1977;van Netten et al., 1998;Winder et al., 2002a). Deze symptomen worden ook wel samengevat onder de naam 'aerotoxic syndroom' (ATS). ...
TCP’s in cabin air of aircrafts. Progress report spring 2014 [report in Dutch]
It is still unclear whether health problems of flight crew and exposure to tricresyl phosphates (TCPs) in the aircraft cabin air are related. The "aerotoxic syndrome" would cause neurological symptoms to some crew members, such as loss of concentration, depression and tremors. A literature study of the RIVM shows that the cause of these health problems among aircrew is still uncertain. TCPs are a constituent of engine oil and can ‘leak’ into the cabin through the air intake. To gain more clarity, more knowledge is required.
For example, more insight is needed on the specific hazard of the different types of TCPs, the exact exposure concentrations of flight crew, now and in the past, and the individual susceptibility of humans to the substance. In addition, it is important to evaluate whether the current standards are sufficiently protective. It is recommended to investigate these aspects on an international scale with stakeholders in the aviation industry and research institutions. The involvement of the aviation sector is important to obtain information on issues specific for aviation, such as the number of hours flown by pilots and the operation of the engines.
The RIVM study was prompted by questions from the House of Representatives. The research was initiated by a two-track approach. First, information on the presence of TCPs in engine oil of aircrafts is found and hazardous effects of TCP are evaluated. RIVM evaluates TCPs within the chemicals legislation REACH (Registration, Evaluation, Authorisation and restriction of CHemicals) and therefore possesses confidential information from manufacturers on the composition of engine oil. Secondly, the possible causes of health problems were analysed based on a literature search. The results are used to discuss TCP measurements in the cockpit of aircrafts, as performed by TNO in 2013.
Key words
Tricresyl phosphate (TCP), ToCP, aircrafts, aerotoxic syndrome
... It should thus be assumed that residue collected on the recirculation filter is a complex combination of normally occurring materials (i.e., clothing fibers and bioeffluents) and "incident" material. Many types of incidents could be selected, but the presence of engine oil particulates in the bleed air has been of considerable interest for many years, making it a logical choice [5][6][7][8][9][10][11]. The objective of this study is to show a link between contaminates measured on the filter and a type of air-quality incident. ...
The current research examines the possibility of using recirculation filters from aircraft to document the nature of air-quality incidents on aircraft. These filters are highly effective at collecting solid and liquid particulates. Identification of engine oil contaminants arriving through the bleed air system on the filter was chosen as the initial focus. A two-step study was undertaken. First, a compressor/bleed air simulator was developed to simulate an engine oil leak, and samples were analyzed with gas chromatograph-mass spectrometry. These samples provided a concrete link between tricresyl phosphates and a homologous series of synthetic pentaerythritol esters from oil and contaminants found on the sample paper. The second step was to test 184 used aircraft filters with the same gas chromatograph-mass spectrometry system; of that total, 107 were standard filters, and 77 were nonstandard. Four of the standard filters had both markers for oil, with the homologous series synthetic pentaerythritol esters being the less common marker. It was also found that 90% of the filters had some detectable level of tricresyl phosphates. Of the 77 nonstandard filters, 30 had both markers for oil, a significantly higher percent than the standard filters.
... Although rare, fume events potentially contain harmful and toxic components from the pyrolized aircraft engine oil which is believed to be the source of the odor and smoke [23,24]. It has been suggested that exposure to the contaminated air of a fume event is the primary cause of short-term and chronic illness, and, as a result, fume events have gained the attention of both pilot and flight attendant unions and the FAA [25][26][27]. ...
... Incidenteel is er sprake van een al dan niet zichtbaar 'fume event', een geurende rookwolk die de cockpit of de cabine vult. 9 Schattingen over de frequentie hiervan tijdens vluchten variëren van 1 op 2000 tot 1 op 66-131. 7 Bij een motortemperatuur boven de 350ºC leiden chemische reacties tot de vorming van onder meer koolstofmonoxide en een complex toxisch mengsel waarvan 1-5% bestaat uit TCP. 10 TCP is een mengsel van 10 verschillende isomeren; de isomeer TOCP is toxischer dan de meta-en paravormen. ...
- Although the air from the turbine engines of commercial jet aircraft is used chiefly for propulsion some is also used to refresh and replenish air in the cabin.- As a result of oil-seal leakage, pyrolysed engine oil or lubricating oil can contaminate cabin air via the aircraft's ventilation system, and flight crew and passengers can then inhale the combusted fumes.- Exposure to emissions from cabin air, whether polluted or not, is associated with certain health risks.- This phenomenon is known as the aerotoxic syndrome or ´cabin contamination´.- The symptoms are non-specific, consisting predominantly of fatigue and mild cognitive impairment.- Possible adverse health effects are attributed factors including organophosphate tricresyl phosphate, a component of aircraft engine oil that is potently neurotoxic.
... Respiratory complaints among aircrew are particularly prominent. Published studies [10,[16][17][18][19][20][21][22] have drawn attention to respiratory abnormalities in previously healthy aircrew who were predominantly nonsmokers, who experienced symptoms following an aircraft cabin fume event. These complaints are consistent with lung injury secondary to hydrocarbon inhalation and, in many cases, the abnormalities have been irreversible. ...
... 23,[37][38][39] Exposure to organophosphate turbine oil additives during such incidents has been suggested as potential group of contaminants of special toxicological interest in this regard. 24,28,40 Organophosphate oil additives can be sampled both by filter and adsorbent methodology approaches, but is favored by sampling on filters or combined filter/adsorbent samplers due to their semi-volatility. 35 Van Netten has recently constructed an incident sampler specially tailored to sample airborne organophosphate contaminants during smoke-in-cabin incidents based on filter sampling. ...
Suddenly occurring and time limited chemical exposures caused by unintended incidents might pose a threat to many workers at various work sites. Monitoring of exposure during such occasional incidents is challenging. In this study a compact, low-weight and personal semi-automatic pumped unit for sampling of organic vapor phase compounds from occupational air during sporadic and suddenly occurring incidents has been developed, providing simple activation by the worker potentially subjected to the sudden occurring exposures when a trained occupational hygienist is not available. The sampler encompasses a tube (glass or stainless steel) containing an adsorbent material in combination with a small membrane pump, where the adsorbent is capped at both ends by gas tight solenoid valves. The sampler is operated by a conventional 9 V battery which tolerates long storage time (at least one year), and is activated by pulling a pin followed by automatic operation and subsequent closing of valves, prior to shipping to a laboratory. The adjustable sampling air flow rate and the sampling time are pre-programmed with a standard setting of 200 mL min(-1) and 30 min, respectively. The average airflow in the time interval 25-30 min compared to average airflow in the interval 2-7 min was 92-95% (n = 6), while the flow rate between-assay precisions (RSD) for six different samplers on three days each were in the range 0.5-3.7%. Incident sampler recoveries of VOCs from a generated VOC atmosphere relative to a validated standard method were between 95 and 102% (+/-4-5%). The valves that seal the sampler adsorbent during storage have been shown to prevent an external VOC atmosphere (500 mg m(-3)) to enter the adsorbent tube, in addition to that the sampler adsorbent is storable for at least one month due to absence of ingress of contaminants from internal parts. The sampler was also suitable for trapping of semi-volatile organophosphates.
... [28][29][30][31][32][33][34][35] OPs in turbine oils have been suggested as major contaminants of concern in airplane cabin air during so called smoke-in-cabin incidents. [35][36][37][38][39][40] However, exposure to OPs from turbine and hydraulic fluids through vapors and aerosols may also occur during aviation ground personnel working operations. 41 Technician work may include exchange of oils, repair and maintenance of pressurized hydraulic systems and engines. ...
This study describes the potential for occupational exposure to organophosphates (OPs) originating from turbine and hydraulic oils, among ground personnel within the aviation industry. The OPs tri-n-butyl phosphate (TnBP), dibutyl phenyl phosphate (DBPP), triphenyl phosphate (TPP) and tricresyl phosphate (TCP) have been emphasized due to their use in such oils. Oil aerosol/vapor and total volatile organic compounds (tVOCs) in air were also determined. In total, 228 and 182 OPs and oil aerosol/vapor samples from technician and loader work tasks during work on 42 and 21 aircrafts, respectively, were collected in pairs. In general, the measured exposure levels were below the limit of quantification (LOQ) for 84%/98% (oil aerosol) and 82%/90% (TCP) of the samples collected during technician/loader work tasks. The air concentration ranges for all samples related to technician work were <LOQ-0.24 (oil aerosol) and <LOQ-9.4 (OPs) mg m(-3), with the highest OP exposure levels measured during wheel well maintenance. For loader work the corresponding air concentration ranges were <LOQ-2.4 (oil aerosol) and <LOQ-0.052 (OPs) mg m(-3), with the highest exposure levels measured during loading from jet engine aircrafts. Investigation of provoked exposure situations revealed substantially higher exposure levels of the contaminants when compared to regular conditions, illustrated by oil aerosol and TCP concentrations up to 240 and 31 mg m(-3), respectively. The tailored OP and the general oil aerosol sampling methods were compared, displaying the advantages of tailored OP sampling for such exposure assessments.
... It was suggested that exposure to fumes in aircraft from hydraulic fluids and lubricants has been associated with acute irritation of the eyes and throat and gastrointestinal, respiratory and nervous system effects, and with chronic central nervous system and immunological effects. Neurological or neuropsychological symptoms reported include headaches, dizziness, fainting, blurred vision, disorientation, memory loss and lack of coordination, as well as symptoms such as nausea and respiratory difficulties (ATSB, 1997;Balouet and Winder, 2000;Rayman and McNaughton, 1983;SBAI, 1999;Tashkin et al,1983;van Netten, 1998). However, other interviewees stated a number of US studies have found levels of air pollutants in aircraft cabin environments to be within specified regulations and guidelines (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Occupational Safety and Health Administration, Federal Aviation Authority and Joint Aviation Authority Airworthiness Standards), with the occasional exception of ozone (O'Donnell et al, 1991;Pierce et al,1999;Spengler et al,1997). ...
A consultation was undertaken to investigate the views and concerns of stakeholders in the aircraft industry about the possible harmful effects on personal health, comfort and safety of aircraft cabin environments.
Stakeholders were identified from a variety of sources including Government agencies, the Internet, House of Lords inquiry, and suggestions of intervie wees. They represented: aircraft crews, aircraft con structors and engineers, government departments and authorities, holiday/flight companies, insurance com panies, non-governmental organisations, occupational health physicians, passenger representatives, and inde pendent researchers and consultants. Eighty-seven were contacted of which 57 were interviewed over the telephone using a semi-structured questionnaire. Their concerns were transcribed into a standard format and analysed qualitatively. Key stakeholders, along with Government officials, were invited to a workshop to discuss and prioritise the issues raised during the inter views.
The main concerns expressed by the participants fell into five main areas: deep vein thrombosis, air qual ity, infection, cosmic radiation, and jet lag and work pat terns. In addition, a number of safety concerns were raised as well as comments on the provision of appro priate advice to passengers. It was generally felt that further research was required on each of these subjects, as well as an improvement in the quality; quantity and availability of information provided for passengers prior to boarding a flight.
... Finally, SHS exposure is but one factor that may have contributed to our findings. Airplane cabin supply air is known to be contaminated with smoke and fumes containing pyrolyzed engine oil and/or hydraulic fluid which has been documented to cause respiratory complaints [19,20]. The air supply can also contain ozone gas in-flight and deicing fluid and/or exhaust fumes during ground operations212223. ...
Little is known about long-term adverse health consequences experienced by flight attendants exposed to secondhand smoke (SHS) during the time smoking was allowed on airplanes. We undertook this study to evaluate the association between accumulated flight time in smoky airplane cabins and respiratory tract diseases in a cohort of never smoking flight attendants.
We conducted a mailed survey in a cohort of flight attendants. Of 15,000 mailed questionnaires, 2053 (14%) were completed and returned. We excluded respondents with a personal history of smoking (n = 748) and non smokers with a history of respiratory tract diseases before the age of 18 years (n = 298). The remaining 1007 respondents form the study sample.
The overall study sample was predominantly white (86%) and female (89%), with a mean age of 54 years. Overall, 69.7% of the respondents were diagnosed with at least one respiratory tract disease. Among these respondents, 43.4% reported a diagnosis of sinusitis, 40.3% allergies, 30.8% bronchitis, 23.2% middle ear infections, 13.6% asthma, 13.4% hay fever, 12.5% pneumonia, and 2.0% chronic obstructive pulmonary disease. More hours in a smoky cabin were observed to be significantly associated with sinusitis (OR = 1.21; p = 0.024), middle ear infections (OR = 1.30; p = 0.006), and asthma (OR = 1.26; p = 0.042).
We observed a significant association between hours of smoky cabin exposure and self-reported reported sinusitis, middle ear infections, and asthma. Our findings suggest a dose-response between duration of SHS exposure and diseases of the respiratory tract. Our findings add additional evidence to the growing body of knowledge supporting the need for widespread implementation of clean indoor air policies to decrease the risk of adverse health consequences experienced by never smokers exposed to SHS.
The term aerotoxic syndrome has been proposed to describe a constellation of symptoms reported by pilots and cabin crew following exposure to possible (neuro)toxic substances in cabin air. Several organ systems are involved. Potentially toxic chemicals emanate from hydraulic fluids and engine oil and include organophosphate compounds, solvents and carbonmonoxide. Oil contamination in the compressor will result in nanoparticles in bleed air under most operating conditions. Overfilling of oil or faulty seals lead to oil leaks which permit ultrafine particles to cross oil seals. Extremely high temperatures in aircraft engines may alter the composition of the original oil and create new toxic compounds. De-icing fluids and the use of insecticides may also contaminate cabin air.
Regulatory authorities estimate fume events (incidental smells, smoke or mist inside an airplane) happen on 0.2–0.5% of flights. Objective evidence of exposure is often lacking and indirect proof in the form of biomarkers is scarce. The underlying mechanisms leading to chronic symptoms, extend beyond cholinesterase inhibition. Individual genetic differences in the ability to metabolize solvents and organophosphates may explain why long-term intermittent low-level exposure causes ill health in some people.
We discuss the current evidence for central nervous system injury in aerotoxic syndrome and propose diagnostic criteria to argue for its recognition as occupational disorder. Prospective studies and a proactive attitude of authorities are required. Nano-aerosols as vehicles for toxic compounds should stimulate the development of bleedless aircraft. Until then the “aircraft cabin of the future” should have continuous cabin air monitoring and filter technology to make flying safe for everyone.
We reviewed 47 documents published 1967–2019 that reported measurements of volatile organic compounds (VOCs) on commercial aircraft. We compared the measurements with the air quality standards and guidelines for aircraft cabins and in some cases buildings. Average levels of VOCs for which limits exist were lower than the permissible levels except for benzene with average concentration at 5.9 ± 5.5 μg/m3. Toluene, benzene, ethylbenzene, formaldehyde, acetaldehyde, limonene, nonanal, hexanal, decanal, octanal, acetic acid, acetone, ethanol, butanal, acrolein, isoprene and menthol were the most frequently measured compounds. The concentrations of semi‐volatile organic compounds (SVOCs) and other contaminants did not exceed standards and guidelines in buildings except for the average NO2 concentration at 12 ppb. Although the focus was on VOCs, we also retrieved the data on other parameters characterizing cabin environment. Ozone concentration averaged 38 ppb below the upper limit recommended for aircraft. The outdoor air supply rate ranged from 1.7 to 39.5 L/s per person and averaged 6.0 ± 0.8 L/s/p (median 5.8 L/s/p), higher than the minimum level recommended for commercial aircraft. Carbon dioxide concentration averaged 1315 ± 232 ppm, lower than what is permitted in aircraft and close to what is permitted in buildings. Measured temperatures averaged 23.5 ± 0.8°C and were generally within the ranges recommended for avoiding thermal discomfort. Relative humidity averaged 16% ± 5%, lower than what is recommended in buildings.
Prioritization of new and emerging chemical risks for workers and follow-up actions
It happens quite often that there is little or no knowledge of the harmful effects of substances that are used by workers. One of the reasons for this is the fact that the risk assessment is usually based on toxicological
tests following oral exposure, while workers are exposed via the airways and the skin. New and emerging risks (NERCs) continue to be reported despite existing laws and regulations put in place to limit the risks of
dangerous substances at work.
To prevent workers from falling ill because of these NERCs, RIVM is arguing for a system that identifies NERCs as soon as possible. In 2013, RIVM published a list of 43 NERCs that may have adverse effects on health after inhalation or dermal exposure. In this report, this list was extended to 49 NERCs and subsequently prioritized to address those substances that deserve the most attention.
The NERCs were prioritized by mapping both the potential risk and the use of the substance in the Netherlands. Three categories were identified based on specific information: for a substance of the first category there is an urgent need to investigate a possible causal relationship between the exposure and the effect on health, and to take risk reduction measures if needed. The second category requires action to be taken, but not immediately. The third category requires minimal action.
In addition to this, an inventory was made showing the extent to which these 49 substances are already being regulated by the European chemicals legislation REACH or other legislation. Based on this
information, the Netherlands’ Bureau REACH, together with the Ministries (SZW, VWS and I&M) and the Inspectorates (Inspectorates of SZW, NVWA and ILT) can decide whether or not sufficient measures
have already been taken for the substances with the highest priorities, and whether additional measures are needed.
Pyrolysed engine oil sometimes contaminates the ventilation supply air on commercial aircraft, exposing crew members and passengers to oil fumes. Aircraft occupants have documented both acute and chronic symptoms, largely neurological and respiratory, during and after such exposures. However, aviation regulators do not require airlines to either clean or monitor the ventilation supply air for oil-based contaminants and there is no central reporting system for either crew members or passengers. This paper presents the debate over whether existing evidence of ill health and compromised flight safety warrants engineering and administrative controls to protect crew members in particular. It also describes the regulatory frameworks for aviation workplace safety/health and air supply system design/maintenance in the US. The authors recommend a combination of engineering and administrative controls to prevent exposure to oil fumes on aircraft.
Pilots and flight attendants are concerned about the perceived failure of the aviation industry and its regulators to address the problem of cabin air contamination and the health effects among aircrew following exposure to these contaminants. The aim of this paper was to survey a self-selected group of affected commercial aircrew (including 39 pilots) and document their symptoms and treatment. Various symptoms were reported by the aircrew, but neurological symptoms were present in nearly all cases. The symptoms affected the performance of the aircrew during flight, and there was a reluctance to report the fume events and symptoms. The problem of fume events represents a threat to the safety of those on board the aircraft and unacceptable health issues among aircrew. Although the problem is continuing to occur, it is not being systematically addressed.
This paper describes a research project that responds to the United States legislative requirements to establish health surveillance in relation to bleed-air events ("incident reporting") and to analyse filter samples obtained during air quality incidents ("incident monitoring"). The incident reporting component will develop health surveillance systems to collect data on potential health effects. The incident monitoring component completes the development, testing and deployment of a portable air-sampling device to be used by crew members to collect air contaminant data in aircraft. The incident reporting and monitoring systems will be tested in a feasibility study and will provide feedback from crew on the developed instruments, train crew to collect air samples and use the health surveillance system, and deploy samplers to crew. The final product will be a design for a full-scale study, which would produce the scientific rigour necessary to sort out possible relationships between exposures and subsequent symptom reports and confounding circumstances.
The term "aerotoxic syndrome" was proposed in 1999 to describe the association of symptoms observed among flight crew and cabin crew who have been exposed to hydraulic fluid or engine oil vapours or mists. A descriptive epidemiological study was conducted to investigate the health effects of aircrew through a questionnaire mail-out. Most of the respondents (88%) reported that symptoms occurred after exposure to engine oil or hydraulic fluid leaks which caused odours and/ or visible contamination in the cabin. Invariably, aircrew directly attributed their symptoms to exposure to in-cabin airborne contaminants. A comparison between 18 respondents from the United States and the 50 Australian respondents shows significant similarities in reported symptoms. There was sufficient commonality in reported symptoms to conclude a symptom basis for aerotoxic syndrome.
This descriptive study reports the results of assays performed to detect circulating autoantibodies in a panel of 7 proteins associated with the nervous system (NS) in sera of 12 healthy controls and a group of 34 flight crew members including both pilots and attendants who experienced adverse effects after exposure to air emissions sourced to the ventilation system in their aircrafts and subsequently sought medical attention. The proteins selected represent various types of proteins present in nerve cells that are affected by neuronal degeneration. In the sera samples from flight crew members and healthy controls, immunoglobin (IgG) was measured using Western blotting against neurofilament triplet proteins (NFP), tubulin, microtubule-associated tau proteins (tau), microtubule-associated protein-2 (MAP-2), myelin basic protein (MBP), glial fibrillary acidic protein (GFAP), and glial S100B protein. Significant elevation in levels of circulating IgG-class autoantibodies in flight crew members was found. A symptom-free pilot was sampled before symptoms and then again afterward. This pilot developed clinical problems after flying for 45 h in 10 d. Significant increases in autoantibodies were noted to most of the tested proteins in the serum of this pilot after exposure to air emissions. The levels of autoantibodies rose with worsening of his condition compared to the serum sample collected prior to exposure. After cessation of flying for a year, this pilot's clinical condition improved, and eventually he recovered and his serum autoantibodies against nervous system proteins decreased. The case study with this pilot demonstrates a temporal relationship between exposure to air emissions, clinical condition, and level of serum autoantibodies to nervous system-specific proteins. Overall, these results suggest the possible development of neuronal injury and gliosis in flight crew members anecdotally exposed to cabin air emissions containing organophosphates. Thus, increased circulating serum autoantibodies resulting from neuronal damage may be used as biomarkers for chemical-induced CNS injury. The authors thank all of the participants who volunteered to take part in this case study. The technical work of Dr. Hagir B. Suliman and the art work of Sheref M. Abou-Donia are appreciated. This study was supported in part by the Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA.
Industry, government, and labor representatives have all acknowledged that air supply sys-tems on commercial aircraft sometimes get contaminated with pyrolyzed engine oil or hydraulic fluid, but efforts to define "sometimes" have been lacking. Despite the lack of attention it has received, the answer to this "how often" question is important because it will influence the willingness of industry, as well as regulators and legislators, to develop and implement control measures to prevent such air supply contami-nation. To address this data gap, an industrial hygienist collected reports of air supply contamination over an 18-month period January 2006 through June 2007 from the following sources, all per defined inclusion criteria: 1 Service Difficulty Reports SDR and Accident and Incident Data System AIDS reports that airlines submitted to the Federal Aviation Administration FAA; 2 incidents that flight attendants docu-mented with one of 20 airlines and copied to one crewmember labor union; and 3 newspaper clips identified in online searches. A qualified airline mechanic reviewed each SDR and AIDS report with an oil or hydraulic fluid-related mechanical defect that did not explicitly mention oil or hydraulic fluid in combination with a specific word that indicated air supply contamination i.smoke" to determine its eligibility. The resulting dataset of 470 air supply contamination events reported in the U.S. commercial fleet over an 18-month period translates into an average of 0.86 events per day and includes 350 incidents reported by airlines to the FAA, 115 reported flight attendants to their airline, and 37 incidents reported by at least one newspaper. There was limited overlap between sources. The data are discussed in detail along with commentary on whether and how the data are representative, the health and operational costs associated with air supply contamination, and some preventive measures.
Indoor air in occupied buildings is always more polluted from human-sourced contaminants than the air outside the building. This is true for modern buildings constructed during the past decade as well as for primitive shelters erected centuries or millennia ago. It follows that a continuous source of outdoor air is required to prevent the degradation of indoor air from contaminants arising from people and their activities. This was realized historically by the inventors of roof vents for exhaust of fire smoke and by early designers of openable windows for introduction of make-up (outdoor) air.
Aircraft air quality incidents from bleed-air contamination by engine oil occur at frequencies that range from 3.8-0.09 per 1,000 cycles, resulting in health complaints from crew members. Central nervous system symptoms are predominant, followed by gastrointestinal and respiratory systems. Laboratory simulations have identified the presence of tri-cresyl phosphate (TCP) isomers in the air, along with carbon monoxide (CO). The former is an oil constituent and the latter a pyrolysis product. Both agents affect the central nervous system. Analysis of air recirculating filters from aircraft shows the presence of TCP, indicating respiratory exposure. Up to 60 ppm of CO have been measured by a pilot during flight. Direct exposure measurements for TCP are now possible with the VN sampler - a small, inexpensive self-contained air sampler that can be activated by any crew member during a fume incident. Incorporation of a CO detector into this sampler is currently being contemplated.
The cabin of an airplane is aspecialised working environment and should be considered
as such. The oils and hydraulics used in airplane engines are toxic, and specific ingredients of
such materials are irritating, sensitising and neurotoxic. If oil or hydraulic fluids leak out of
engines, this contamination may be in the form of unchanged oil/fluid, degraded oil/fluid from long
use in the engine, combusted oil/fluid or pyrolised oil/fluid, in the form of gases, vapours, mists
and particulate matter. If leak incidents occur and the oil/fluid is ingested into bleed air and
is passed to the flight deck and passenger cabins of airplanes in flight, aircrew and passengers may
be exposed to contaminants that can affect their health and safety. Where contamination of air in
the flight deck and passenger cabin occurs that is sufficient to cause symptoms of discomfort, fatigue,
irritation or toxicity, this contravenes the air quality provisions of Federal Aviation Regulations,
most notably FAR 25.831. Symptoms of immediate or short-term nature and reported by exposed staff
in single or few leak incidents are consistent with the development of irritation and discomfort.
Symptoms of along-term nature (that is, sustained symptoms for at least six months) reported
by some exposed staff following small to moderate numbers of leak incidents are consistent with the
development of an irreversible discrete occupational health condition, termed aerotoxic syndrome.
Features of this syndrome are that it is associated with air crew exposure at altitude to atmospheric
contaminants from engine oil or other aircraft fluids, temporarily juxtaposed by the development of
aconsistent symptomology including short-term skin, gastro-intestinal, respiratory and nervous
system effects, and long-term central nervous and immunological effects.
Symptoms reported by passengers and crewmembers on commercial aircraft are described according
to individual air quality-related sources, including: (1) elevated levels of bioeffluents; (2) infectious
agents; (3) extreme temperatures; (4) exhaust fumes, deicing fluid, fuel fumes, and cleaning products;
(5) heated engine oil and hydraulic fluid; (6)reduced oxygen supply; (7) ozone gas; and (8)
insecticides. Abrief overview of the aircraft regulatory environment and available sources
of data on the hazards and associated health effects is also provided.
Researchers have found, in studies carried out over several years, that many passengers and crew, following their recent flights in commercial jet aeroplanes, have become unwell, with a range of symptoms in common. This condition, which has not yet been officially recognised, is called Aerotoxic Syndrome (AS). It seems to be caused, primarily, by neurotoxic organophosphates contaminating the air circulating in jet cabins. Patients with such symptoms may visit their GPs, who then arrange diagnostic tests. Some of their symptoms fall within the jurisdiction of diagnostic neurophysiological investigations, but neurophysiology practitioners may be unaware of this syndrome. Until AS is officially recognised as an illness, and guidelines for diagnostic procedures established, patients requiring specific investigations may not be appropriately referred, or tests may be performed unnecessarily. This report seeks to stimulate debate within the field, and facilitate studies, if needed, to help define the diagnostic criteria.
As aircraft operators have sought to substantially reduce propulsion fuel cost by flying at higher altitudes, the energy cost of providing adequate outside air for ventilation has increased. This has lead to a significant decrease in the amount of outside air provided to the passenger cabin, partly compensated for by recirculation of filtered cabin air. The purpose of this review paper is to assemble the available measured air quality data and some calculated estimates of the air quality for aircraft passenger cabins to highlight the trend of the last 25 years. The influence of filter efficiencies on air quality, and a few medically documented and anecdotal cases of illness transmission aboard aircraft are discussed. Cost information has been collected from the perspective of both the airlines and passengers. Suggestions for air quality improvement are given which should help to result in a net, multistakeholder savings and improved passenger comfort.
A small air sampling system using standard air filter sampling technology has been used to monitor the air in aircraft. The device is a small ABS constructed cylinder 5 cm in diameter and 9 cm tall and can be operated by non technical individuals at an instant notice. It is completely self contained with a 4 AAA cell power supply, DC motor, a centrifugal fan, and accommodates standard 37 mm filters and backup pads. The monitor is totally enclosed and pre assembled in the laboratory. A 45 degrees twist of the cap switches on the motor and simultaneously opens up the intake ports and exhaust ports allowing air to pass through the filter. A reverse 45 degrees twist of the cap switches off the motor and closes all intake and exhaust ports, completely enclosing the filter. The whole monitor is returned to the laboratory by standard mail for analysis and reassembly for future use. The sampler has been tested for electromagnetic interference and has been approved for use in aircraft during all phases of flight. A set of samples taken by a BAe-146-300 crew member during two flights in the same aircraft and analyzed by GC-MS, indicated exposure to tricresyl phosphate (TCP) levels ranging from 31 to 83 nanograms/m(3) (detection limit <4.5 nanograms/m(3)). The latter elevated level was associated with the use of the auxiliary power unit (APU) in the aircraft. It was concluded that the air sampler was capable of monitoring air concentrations of TCP isomers in aircraft above 4.5 nanogram/m(3).
The flight crews of aircraft often report symptoms including dizziness, nausea, disorientation, blurred vision and tingling in legs and arms. Many of these incidents have been traced to contamination of cabin air with lubricating oil, as well as hydraulic fluid, constituents. Considering that these air contaminants are often subjected to temperatures in excess of 500 degrees C, a large number of different exposures can be expected. Although the reported symptoms are most consistent with exposures to volatile organic compounds, carbon monoxide, and the organophosphate constituents in these oils and fluids, the involvement of these agents has not been clearly demonstrated. Possible exposure to toxic elements, such as lead, mercury, thallium and others, have not been ruled out. In order to assess the potential of exposure to toxic elements a multi-elemental analysis was done on two hydraulic fluids and three lubricating oils which have been implicated in a number of air quality incidents. A secondary objective was to establish if the multi-elemental concentrations of the fluids tested are different enough to allow such an analysis to be used as a possible method of identifying the source of exposure that might have been present during aircraft air quality incidents. No significant concentrations of toxic elements were identified in any of the oils or hydraulic fluids. The elemental compositions of the samples were different enough to be used for identification purposes and the measurement of only three elements was able to achieve this. Whether these findings have an application, in aircraft air quality incident investigations, needs to be established with further studies.
Incidents of smoke in aircraft cabins often result from jet engine oil and/or hydraulic fluid that leaks into ventilation air, which can be subjected to temperatures that exceed 500 degrees C. Exposed flight-crew members have reported symptoms, including dizziness, nausea, disorientation, blurred vision, and tingling in the legs and arms. In this study, the authors investigated pyrolysis products of one jet engine oil and two hydraulic fluids at 525 degrees C. Engine oil was an important source of carbon monoxide. Volatile agents and organophosphate constituents were released from all the agents tested; however, the neurotoxin trimethyl propane phosphate was not found. The authors hypothesized that localized condensation of pyrolysis products in ventilation ducts, followed by mobilization when cabin heat demand was high, accounted for mid-flight incidents. The authors recommended that carbon monoxide data be logged continuously to capture levels during future incidents.
The small air space available per person in a fully occupied aircraft passenger cabin accentuates the human bioeffluent factor in the maintenance of air quality. The accumulation of carbon dioxide and other contributions to poor air quality that can occur with inadequate ventilation, even under normal circumstances, is related to the volume of available air space per person and various ventilation rates. This information is compared with established air quality guidelines to make specific recommendations with reference to aircraft passenger cabins under both normal and abnormal operating conditions. The effects of respiration on the air quality of any enclosed space from the respiration of a resting adult are estimated using standard equations. Results are given for different volumes of space per person, for zero air exchange, and for various air change rates. The required ventilation rates estimated in this way compared closely with results calculated using a standard empirical formula. The results confirm that the outside air ventilation required to achieve a target carbon dioxide concentration in the air of an occupied enclosed space remains the same regardless of the volume of that space. The outside air ventilation capability of older and more recent aircraft is then reviewed and compared with the actual measurements of cabin air quality for these periods. The correlation between calculated and measured aircraft cabin carbon dioxide concentrations from other studies was very good. Respiratory benefits and costs of returning to the 30% higher outside air ventilation rates and 8% higher cabin pressures of the 1960s and 1970s are outlined. Consideration is given to the occasional occurrence of certain types of aircraft malfunction that can introduce more serious contaminants to the aircraft cabin. Recommendations and suggestions for aircraft builders and operators are made that will help improve aircraft cabin air quality and the partial pressure of oxygen that is available to passengers at minimal cost. Also suggested are some measures that passengers can take to help improve their comfort and decrease their risk of illness, particularly on long-haul flights.
Aircraft disinsection is required by various countries. In-flight spraying with a 2% phenothrin aerosol exposes passengers and crew directly. Residual spaying uses a permethrin emulsions in the absence of passengers and crew and results in dermal and oral exposures. Exposed passengers and crew often complain of, skin rashes, respiratory problems, tingling and numbness in fingertips and lips and burning eyes. A number of formulations were analyzed for their constituents using GLC-Mass. spec. Volatile organic compounds (VOCs) were found in all aerosol preparations including, ethyl benzene and xylene isomers along with phenothrin. Residual sprays contained, cis-, and trans-, permethrins, palmidrol, and occasionally naphthalene. Headspace analysis found methylene chloride and hexene derivatives but not the active ingredients. The known synergistic effects between organophosphates and pyrethrins, based on carboxyesterases inhibition, can be expected in the presence of Tricresylphosphates (TCPs), constituents found in jet engine oils and in some hydraulic fluids. During oil seal failure, the presence of TCP in the ventilation air could explain the increased sensitivity of some crew members and passengers to disinsectants.
Organophosphorus compounds are potent neurotoxic chemicals that are widely used in medicine, industry, and agriculture. The neurotoxicity of these chemicals has been documented in accidental human poisoning, epidemiological studies, and animal models. Organophosphorus compounds have 3 distinct neurotoxic actions. The primary action is the irreversible inhibition of acetylcholinesterase, resulting in the accumulation of acetylcholine and subsequent overstimulation of the nicotinic and muscarinic acetylcholine receptors, resulting in cholinergic effects. Another action of some of these compounds, arising from single or repeated exposure, is a delayed onset of ataxia, accompanied by a Wallerian-type degeneration of the axon and myelin in the most distal portion of the longest tracts in both the central and peripheral nervous systems, and is known as organophosphorus ester-induced delayed neurotoxicity (OPIDN). In addition, since the introduction and extensive use of synthetic organophosphorus compounds in agriculture and industry half a century ago, many studies have reported long-term, persistent, chronic neurotoxicity symptoms in individuals as a result of acute exposure to high doses that cause acute cholinergic toxicity, or from long-term, low-level, subclinical doses of these chemicals. The author attempts to define the neuronal disorder that results from organophosphorus ester-induced chronic neurotoxicity (OPICN), which leads to long-term neurological and neurobehavioral deficits. Although the mechanisms of this neurodegenerative disorder have yet to be established, the sparse available data suggest that large toxic doses of organophosphorus compounds cause acute necrotic neuronal cell death in the brain, whereas sublethal or subclinical doses produce apoptotic neuronal cell death and involve oxidative stress.
Triaryl phosphates including tricresyl phosphate (TCP) and butylated triphenyl phosphates (BTPs) are used in the commercial manufacture of plastics, lubricants, and hydraulic fluids. Recent reports implicate these compounds as endocrine and reproductive toxicants in rodents. The objectives of this study were to develop and characterize a rat model to investigate the mechanism(s) of toxicity of triaryl phosphate-based hydraulic fluids and to elucidate potential mechanistic pathways of toxicity through studies of structural/functional relationships. Groups of male and female rats received daily oral doses of either sesame oil alone or 1.7 g/kg of BTP or 0.4 g/kg TCP in sesame oil vehicle or 2.8 g/kg neat BTP for 20, 40, and 60 days. Light microscopic, morphometric, ultrastructural, and histochemical studies revealed hypertrophy and cholesteryl lipidosis of adrenocortical (both sexes) and ovarian interstitial cells that were progressive with duration of exposure. Minimal degeneration was observed in the adrenal cortex and ovary. TCP caused the most severe lesions in both the adrenal gland and ovary, but the morphologic and histochemical changes produced were similar for both compounds, suggesting a common mechanism of toxicity. Decreased testicular weight and degeneration of seminiferous tubules were detected only in TCP-treated rats. The Fischer-344 rat model using TCP and BTP administered by gavage is a valuable system to study mechanisms of endocrine and reproductive toxicity induced by triaryl phosphate-based hydraulic fluids.
A group of 62 human subjects were exposed for 2.75 h to a mixture of 22 volatile organic compounds known to be indoor air pollutants. Three total concentrations of 0, 5 and 25 mg/m3 of the same 22 compounds were used. The subjects were all healthy and without asthma, allergy, or chronic bronchitis but claimed often to suffer from dry mucous membranes in eyes, nose, or upper airways. By using a questionnaire on 26 different air quality aspects, a significant effect of exposure was found for questions related to general air quality, odour, ability to concentrate, and/or mucous membrane irritation. Continuous evaluation of irritation in eyes, nose, and throat showed significant correlation to exposure both at 5 and 25 mg/m3. The effect was acute and showed no signs of adaptation. A digit span performance test showed decreased scores during exposure.
Under extreme conditions of thermal degradation, a potent neurotoxin, trimethylolpropane phosphate (TMPP), may be formed by reaction of tricresyl phosphate (TCP, an anti-wear additive) and trimethylolpropane esters (TMPE) of carboxylic acids that may be contained in turbine engine lubricant formulations. The neurotoxin is only formed at extreme temperatures (350-700 degrees C), which has minimized concern for use of the synthetic lubricants under intended applications; however, since researchers are often not privy to the proprietary composition of such lubricants, extreme caution should be exercised in studies of or applications of synthetic lubricants degraded under extreme conditions.
The nervous system differs from many other body organs by its central control of vital functions and its low regeneration capacity. Organic solvents have, as a group, been suspected to have neurotoxic effects. Because of their similar physical properties and the fact that in industrial uses, they are often present in various mixtures, organic solvents have also been regarded, unfortunately, to induce common neurotoxic effects. However, it is evident from experimental studies using specified exposure conditions that different organic solvents have very diverse neurotoxic effects and also that the toxic mechanism may differ between acute and chronic exposure. No specific method used to describe a neurotoxic effect or single toxic response can be used for the overall occupational risk assessment of all organic solvents. Each solvent has to be considered as having its own unique toxic effects.
Psychomotor and mental tests involving reaction time, rotor pursuit, short-term memory for digits and letters, and reasoning ability were administered to subjects inhaling up to 5% CO2 in air and in gas mixtures containing 50% O2, The psychomotor and mental tests were given during the 6 min of recovery following 10 min of treadmill running at 80% of aerobic capacity. Although the subjects inhaled the CO2 during the entire exercise and recovery period there was no difference in performance between the CO2 inhalation condition and the control condition for any of the performance measures.
A computer-based physiological model of respiratory gas exchange, which considered variation in inhaled oxygen and carbon dioxide, was modified to include the effects of inhaled carbon monoxide. Output from the modified model consists of 60 variables, including blood, alveolar and tissue gases, ventilatory function and carboxyhemoglobin. Extensive testing demonstrated that this model produced accurate results for known problems and physiologically plausible results for situations in which the results were not empirically known. Estimates of the effects of simultaneous continuously varying exposure to carbon monoxide, oxygen and carbon dioxide cannot be practically obtained with other extant methods. The modified model receives input from two computer files containing environmental and subject physiological variables. These files allow a continuous dynamic multi-gas exposure simulation or actual exposure data profiles. Up to four outputs can be selected for plotting or stored in a file for later analysis.
Synthetic polyol-based lubricating oils containing 3% of either commercial tricresyl phosphate (TCP), triphenylphosphorothionate (TPPT), or butylated triphenyl phosphate (BTP) additive were evaluated for neurotoxicity in the adult hen using clinical, biochemical, and neuropathological endpoints. Groups of 17-20 hens were administered the oils by oral gavage at a "limit dose" of 1 g/kg, 5 days a week for 13 weeks. A group of positive control hens was included which received 7.5 mg/kg of one isomer of TCP (tri-ortho-cresyl phosphate, TOCP) on the same regimen, with an additional oral dose of 500 mg/kg given 12 days before the end of the experiment. A negative control group received saline. Neurotoxic esterase (NTE) activity in brain and spinal cord of hens dosed with the lubricating oils was not significantly different from saline controls after 6 weeks of treatment. After 13 weeks of dosing, NTE was inhibited 23 to 34% in brains of lubricant-treated hens. Clinical assessments of walking ability did not indicate any differences between the negative control group and lubricant-treated hens. Moreover, neuropathological examination revealed no alterations indicative of organophosphorus-induced delayed neuropathy (OPIDN). In hens treated with the positive control, significant inhibition of NTE was observed in brain and spinal cord at both 6 and 13 weeks of dosing; this group also demonstrated clinical impairment and pathological lesions indicative of OPIDN. In conclusion, the results of the present study indicated that synthetic polyol-based lubricating oils containing up to 3% TCP, TPPT, or BTP had low neurotoxic potential and should not pose a hazard under realistic conditions of exposure.
Several studies have shown that some aspects of vision are impaired when exposed to higher than normal CO2 concentrations in air. The effect of moderately increased CO2 concentration on coherent motion perception, however, has not been studied.
Studies in neurophysiology and cell biology have provided evidence that higher than normal CO2 concentration in air affects cell activities from the retina to the cortex, including the V1 area in the visual cortex. We predicted that motion perception may be impaired by moderately increased CO2, since the V1 area is a gateway for visual motion information processing. The purpose of the present work was to investigate the effect of 2.5% CO2 concentration in air on coherent motion perception.
Random dot cinematograms were generated by a computer and served as visual stimuli. A whole-room indirect calorimeter was used for the accurate measurement and control of CO2 concentration in air, and served as the experimental environment. A two-interval-forced choice (2IFC) psychophysical procedure was employed to obtain psychometric functions.
For all three subjects, psychometric functions were shifted to the right when exposed to 2.5% CO2 in breathing air, compared to those using fresh air.
This finding implies that human ability in detecting coherent motion can be temporally impaired when CO2 concentration in air is raised to 2.5%.